In the course of operation of a gas turbine, the adjusting means for adjusting the stator blades of the turbine is subjected to significant loads due to differential thermal effects. As a consequence, the cost of construction and operation of the adjusting means to compensate for these conditions and provide for precise blade adjustment is relatively high.
In order to compensate for differential thermal expansion in the adjusting means, it is known to provide excessive play or high heat elasticity which leads to inaccurate blade adjustment and consequent losses in efficiency in the aero-thermodynamic cycle.
In order to obtain precise adjustment of the stator blades independently of the temperature variations due to various operating conditions, it is disclosed in DE-PS 36 23 001 to connect the support or carrier ring to the turbine housing in a heat insulating manner by several connecting brackets distributed at the periphery of the support ring. The brackets are directly connected to the housing of the turbine by an annular flange and the brackets ar positioned radially above and in the direct vicinity of the turbine housing. The brackets have radial elasticity and elastically support the support ring. The support ring is thus still subjected to considerable thermal effects through the brackets, especially differential heat expansion radially of the housing. The support ring is of U-shape, open at the top, on which the adjusting ring is rotatably supported by rollers in the support ring. The adjusting ring has shoulders which retain the rollers axially and radially to assure precise guidance; however, relatively high friction is developed leading to relatively high adjusting forces. This construction also requires a relatively large radial height for its installation which is often not available, especially in the case of drive turbines.